Design Guidelines for Permanent Tunnel Plugs
CIM Vancouver 2002
Rimas Pakalnis, John Meech,
Permanent tunnel plugs are used for mine closure where it is necesasary to flood the mine workings (usually to prevent ARD generation). The head acting on many tunnel plugs exceeds the head on some of the highest dams in the world. Unlike dams however, these structures are usually designed as "walk-away" structures, not requiring any monitoring or maintenance. Consequently they must be designed and constructed with the utmost care. Guidelines are presented for selecting an appropriate site for the plug, and criteria are provided for design against failure modes such as shear, flexure, excessive seepage, and chemical attack. An update is provided on an experimental plug dubbed the "Millennium Plug" being constructed at the Britannia Mine in B.C. Much like an earthdam, the Millennium Plug is constructed of an impermeable clay core with a graded earth filter. It is expected that this design will provide a more durable tunnel seal compared to concrete, particularly in acidic mine water environments.